Stretched and stabilized yarns and fabrics



June 1968 M. LATHEM ETAL 3,

STRETCHED AND STABILIZED YARNS AND FABRICS Filed D80. 30, 1963 4Sheets$heet 1 James M. LATHEM,

FRA K E. BosoAtz.

j EoBeR-r MMn'r-rulws ATTORNEYS June 1968 I J. M. LATHEM ETAL 3,387,448

STRETCHED AND STABILIZED YARNS AND FABRICS Filed Dec. 50, 1963 4Sheets-Sheet m INVENTQRS m {Q m J'AMes M- LATHEM, 0'0 FRANK E 5980,12.Eag e-I21- M. MATTHEWS 7n 0AM, Cfwumm ATTORNEYS June 11, 1968 J. M.LATHEM ETAL 3,337,448

STRETCHED AND STABILIZED YARNS AND FABRICS 4 Sheets-Sheet 5 Filed Dec.50, 1963 INVENTORS j JWQ ATTORNEYS \..W 2. MSW w BA M M .B.wm E W S T maam, AAB TJRO 2 BY WOAO'YL June 11, 1968 J. M. LATHEM ETAL 3,387,448

STRETCHED AND STABILIZED YARNS AND FABRICS Filed Dec. 30, 1963 4Sheets-Sheet 4 INVENTORS James M. LATuEM,

RANK E. BoBcf-Yz. ROBERT M.MA-r-r|-\svws mzumglmwicl +4 ATTORNEY-SUnited States Patent 3,387,448 STRETQHED AND STABILIZED YARNS ANDFABRICS James M. Lathem, Gainesville, Ga., and Frank E. Bohr),

Jr., and Robert M. Matthews, Charlotte, N.C., assignors to ChadbournGotham, Inc., Charlotte, N.C., a corporation of North Qarolina FiledDec. 30, 1963, Ser. No. 334,415 4 Claims. (Cl. 57152) ABSTRAKIT OF THEDESCLGSURE A stabilized spandex yarn made by stretching the yarn andheat setting in the stretched condition to provide reduced denier,increased yardage and reduced stretch over that which was originallypresent in the yarn.

This invention relates to improved synthetic elastomeric yarns andfabrics which have been drawn and stabilized, and to apparatus by whichthese improved yarns and fabrics may be produced.

In our prior, copending application, Ser. No. 202,192, filed June 13,1962, entitled Method of Drawing, Covering, and Stabilizing SyntheticElastomer Yarn, now Patent No. 3,115,745, dated Dec. 31, 1963, there isdisclosed a method of treating synthetic, elastomeric yarn, such asspandex to make it more suitable for knitting, to stabilize it withrespect to its stretch and retractibility properties and to producelower denier yarn with greater yardage. The method disclosed includesthe steps of elongating a spandex yarn, thereby reducing its diameter,or denier, wrapping the drawn elastomeric yarn with a suitable coveringyarn, such as, for example, multifilament nylon yarn, winding the drawnand wrapped yarn under tension, and heating the drawn and wrapped yarnsufiiciently to stabilize the elastomeric core yarn. The priorapplication also states that the stabilizing heat may be applied to anelongated, bare spandex yarn, or to the tensioned composite yarn, priorto winding on the take-up bobbin. The said application provides acomplete disclosure of the method of treating the yarn, and referencemay be had to that disclosure for the details.

One of the objects of this invention is to provide yarn of certaincharacteristics made in accordance with the method of the priorapplication.

Another object is to provide an improved fabric produced from thetreated yarns mentioned above, or from untreated, wrapped or unwrappedsynthetic, elastomeric yarn, and further treated to enhance itssheerness, hand, and elastic properties, and increase the yardage.

It is also an object of the invention to provide apparatus for producingthe improved yarn and fabric through both batch and continuousprocesses.

Other objects of the invention will become apparent from the followingdescription of practical embodiments thereof, when taken in conjunctionwith the drawings which accompany, and form part of, this specification.

In the drawings:

FIGURE 1 is a somewhat diagrammatic front view of apparatus suitable forelongating and covering synthetic elastomeric yarn and winding thecovered yarn under tension on a bobbin;

FIGURE 2 is a side view of the apparatus shown in FIGURE 2;

FIGURE 3 is a front view of apparatus similar to that of FIGURES 1 and 2but suitable for continuous heat stabilization of the yarn;

FIGURE 4 is a side view of the apparatus of FIG- DRE 3;

FIGURE 5 shows another apparatus for continuous processing of the yarn;

FIGURE 6 is a top plan view of apparatus for simultaneously extendingfabric both longitudinally and transversely;

FIGURE 7 is a side view of the apparatus shown in FIGURE 6;

FIGURE 8 is a plan view of a modified form of fabric stretching andstabilizing apparatus;

FIGURE 9 is a vertical, transverse section through the apparatus ofFIGURE 8, taken on the line 9-9 of FIG- URE 8;

FIGURE 10 is a perspective view of another form of fabric stretchingapparatus;

FIGURE 11 is a top plan view of the structure shown in FIGURE 10;

FIGURE 12 is a top plan view of still another form of fabric stretchingmechanism; and

FIGURE 13 is a side view of the apparatus shown in FIGURE 12.

Following the method set out in the above referred to copendingapplication, a synthetic elastomeric yarn, such as that known asspandex, which is understood to be a polyurethane yarn, is elongated,wrapped with a multifilament nylon yarn, and heat set. The elastomericyarn which forms the core of the composite yarn is preferably in anuntwisted condition, and is maintained in this condition throughout thedrawing and setting operations. The raw, untreated elastomeric yarn withwhich this application is concerned will be capable of stretching in therange of approximately 500% to approximately 700%. It has been foundthat best results are obtained when the core yarn is elongated prior toheat stabilizing within the ratio of 2.5 to 1 and 5 to 1.

The cover yarn preferably is a low denier textured thermoplastic yarn.These yarns impart a soft hand and high coverability at a relatively lownumber of wraps per inch. It is desirable that the number of Wraps perunit length of core yarn be sufficient to cause the strands of wrappingyarn to lay close to the core yarn when the composite yarn is relaxed.It has been found that in most instances, from 10 to 50 turns per inchwill be sufficient. If too many wraps per inch are made the compositeyarn takes on a certain amount of twist liveliness which is notcompletely overcome in the stabilizing operation.

The heat stabilization may take place after the tensioned composite yarnis wound on a package, or in a continuous manner prior to winding. Inview of the fact that shorter time periods are involved in continuousheat setting processes, higher temperatures will be required. Whereas180 F. to 220 F. for periods of from one-half to two hours are suitablefor batch operations, temperatures of from 200 F. to 700 F. are requiredfor continuous processing.

The following examples are illustrative of yarns pro duced by the abovedescribed process:

Example I denier Lycra yarn was processed in a manner heretoforedescribed by a drawing ratio of 4 to 1 and a covering of 24 wraps perinch in left hand direction with 20 denier 7 filaments S twist torquetextured nylon. After processing, the take-up bobbin was steamed at 220F. for a period of one hour. The resultant yarn performed satisfactorilyon a circular knitting machine of the type used in the manufacture ofladies seamless hosiery. A soft pleasing hand was noted in the fabric.The composite yarn was found to have a relaxed denier of approximately110. The Lycra core yarn, which was a originally 140 denier, was foundto be approximately 80 denier. The composite yarn has a stretch of 170%.

Example II 70 denier Lycra yarn was drawn at a ratio of 3.9 to 1 whilebeing covered with 40 wraps per inch in a left hand direction. The wrapyarn was 15 denier, 3 filaments S twist torque textured nylon. Afterprocessing, the take-up bobbin was steamed at 220 F. for one hour. Theresultant composite yarn had a denier of approximately 65. The Lycracore yarn had a denier of approximately 40. The composite yarn had astretch of approximately 175%.

The resultant composite yarn may be used for knitting various articles,such as girdles, underwear, hose, etc., or knitted or woven into tubularform, flat goods, etc. and it has been found that the resultinggarments, or piece goods, may be further enhanced and the yardagegreatly increased by a subsequent treatment of stretching and heatstabilizing.

With a fabric, whether piece goods, tubular or formed into a shapedgarment, such as hose, there is generally both longitudinal andtransverse extension and stabilization while the fabric is extended. Ifthe fabric is stretched equally in both directions, the basic structuralpattern will be unchanged, except that it will be more open, but thefabric will be more sheer and have a much softer hand.

The amount of stretch which can be given a fabric, within practicallimits, is from 30% to 250%. The degree to which the fabric can bestretched and the amount of stretch which will be retained after heatsetting, will depend to some extent on how the fabric is made. The typeof yarn, stitch size of knit goods, amount of tension on the yarn, andpossibly other factors will have a bearing on the amount of stretch tobe given a particular fabric.

An illustrative but non-limiting example of fabric and its treatmentconcerns a tricot fabric made from yarn processed as above described.The yarn was made from a 70 denier spandex core drawn with a 4 to 1ratio, and wrapped in a Z direction, forty turns per inch with 15denier, 3 filament, S torque textured nylon yarn and stabilized withsteam for two hours at 210 F. The wrapped and stabilized yarn had astretch of 175%. This yarn was knit on a tricot machine, and the fabricwas stretched and stabilized with steam at 270 F. for 30 minutes. Thefollowing results were noted:

The resulting fabric was of much finer quality than before treatment, itwas sheerer, softer, and, although freely stretchable, had lessretractive pull. The fabric had increased in size and quality.

Other types of fabric similarly treated showed equally good results.

Several types of apparatus for treating the yarn and the fabric asdescribed have been designed and these are shown on the accompanyingdrawings.

Referring first to FIGURES 1 and 2, there is shown a supply bobbin 1,for spandex yarn 2, which is drawn by face contact at a constant rate ofspeed by drive roller 3. The yarn is fed from bobbin 2 over a guide roll4 and through a hollow spindle 5, driven by a belt 6.

Spindle 5 ca ries a supply bobbin 7 for wrapping yarn 8. Bobbin 7 isrotated in such manner than it will cause the yarn 8 to wrap on andaround the spandex yarn as it travels upward from the spindle 5. Thespandex yarn Wrapped with the yarn 8 produces a composite yarn 9 whichpasses through a traverse guide 10 and onto a takeup bobbin 11. Thetake-up bobbin is driven at a constant rate of speed by a take-up driveroll 12.

The speed of the drive roll 3 is lower than that of takeup drive roll 12so as to draw out the spandex yarn to increase its yardage and reduceits diameter. The relative speeds of the two drive rolls are determinedby the percentage of elongation desired in the spandex yarn. Asindicated above, an elongation ratio of 4 to 1 has been found practicaland desirable, but other ratios can be used and the relative driveroller speeds will be set accordingly.

When using apparatus as shown in FIGURES l and 2, the composite yarn 9will be wound on bobbin 11 under tension, and the wound-packagestillheld under tension will be placed in a suitable steam cabinet andheat stabilized.

In FIGURES 3 and 4, a modified apparatus is shown for continuouslydrawing, wrapping and stabilizing the yarn. In this case, spandex yarn13 is fed from bobbin'14 at a constant rate by drive roll 15. The yarnpasses over guide roll 16, through hollow spindle 17 and toward a lower,fixed, pigtail guide 18. Spindle 17 carries wrap yarn bobbin 19 and wrapyarn 20 is caused to wrap about yarn 13 between the end of spindle 17and pigtail guide 1 8. Thus, the pigtail serves to ensure completion ofthe wrap ping operation beneath the pigtail and as an aligning guide tohold the spandex yarn centered within the spindle. From pigtail 18,composite yarn 21 is drawn over the face of a heater block 22. The blockmay be any means for transferring a controlled and adequate amount ofthe heat to the yarn to stabilize it. The drawing shows a diagrammaticrepresentation of a thermostatically controlled electric resistanceheater, with the temperature being regulated by a thermostat 23. Theyarn then goes through an upper pigtail guide 24 in vertical alignmentwith lower pigtail guide 18, through traverse guide 25 and onto atake-up bobbin 26 driven by drive roll 27. It will be noted that theheater block is positioned so that its operative face is offset from thevertical center line of the guides 18 and 24 so that the composite yarnis held in intimate contact with the face of the block. In thisstructure, as in that previously described, the relative speeds of thesupply bobbin 14 and takeup bobbin 26 determine the percentage ofelongation of the spandex yarn.

FIGURE 5 shows a modification of the structure shown in FIGURES 3 and 4,wherein a heater tube 28 is substituted for the heating block. The tubeis hollow, and may be wrapped with a resistance wire 29 which may beencased in glass. The composite yarn 30, formed of spandex yarn 31 fromsupply bobbin 32 and wrap yarn 33 from bobbin 34 passes through guide35, tube 28, and guide 36, and is wound on bobbin 37. Here, again, thedifferential in speed between the spandex supply bobbin and the takeupbobbin is used to produce elongation in the elastomeric yarn. Thecomposite yarn is stabilized as it passes through the heater tube.

Good results have been obtained with this apparatus with yarn of lightor heavy denier. The tube may be stainless steel, of considerablelength, say 24 inches, and of small inside diameter of the order of $4of an inch. Temperatures of from 200 F. to 700 F. are suitable, but somedifiiculty may be encountered at the higher temperatures duringthread-up due to the tendency of the yarn to melt.

It will be obvious that in either that form of the invention shown inFIGURES 3 and 4, or other form shown in FIGURE 5, the heater may bepositioned below the wrapping point so that the elastomeric yarn will bestabilized prior to wrapping. With both types of apparatus bare spandexyarns may be processed by eliminating the wrap yarn supply.

When it is desired to increase the size of a fabric in accordance withthe method previously described, longitudinal stretch can be obtained inthe same manner as is 5. used for elongating yarn filaments, that is, bydifferent speeds of supply and wind-up. A different problem arises,however, when it becomes necessary to provide widthwise stretchsimultaneously with longitudinal stretch. Several mechanisms have beendevised for accomplishing this.

In FIGURES 6 and 7 one form of apparatus for providing both longitudinaland widthwise stretch is shown. The fabric 38 to be processed isdelivered from a supply beam 39 which is rotated by means of contactdrive roller 40. The fabric is taken up on a take-up beam 41 driven bydrive roller 42. The speed differential between drive roller 40 anddrive roller 42 is set to give the desired longitudinal stretch.

Intermediate the supply and take-up beams there is a plurality ofrollers 43, 44 and 45, extending transversely to the direction of fabrictravel. The rollers are located substantially in the horizontal plane ofthe supply and take-up beams, and the fabric follows an undulating pathtravelling over the roller 43, under the roller 44 and over roller 45.This ensures ample surface contact between the rollers and fabric topermit the rollers to exert a positive force on the fabric. The rollersare tapered from their centers to their ends so that the fabric will beforced to spread widthwise. By rotating the rollers 43, 44 and 45 atsurface speeds faster than the linear speed of the fabric, the spreadingaction will be increased.

Each tapered roller is hollow and has a resistance wire 46 wound insideto heat the roller, so that the roller surface can transfer heat to thefabric and set it in its stretched condition. The rollers may havecollection rings 47 at one end to which the wires are connected.

With the above-described arrangement, the fabric will be stretchedlongitudinally due to beam speed differential, and transversely in stepsby the tapered rollers. The fabric is set by each roller, and this willcause the fabric to spread to a greater extent at each roller as theheat setting at the previous roller has reduced the tendency of thefabric to contract. The fact that the rotational speed of the taperedrollers exceeds the forward travel of the fabric assures maximum heattransference to the fabric.

A modification of the continuous fabric stretching apparatus justdescribed is shown in FIGURES 8 and 9. In this form of the apparatus,the supply and take-up beams 48 and 49 are driven by contact driveroller 50 and 51, respectively. The take-up is faster than the supplyfeed to provide desired longitudinal elongation. Between the two beamsthere is a plate 52 which has a transversely convex upper surface 53.The surface area increases progressively with the distance from thesupply beam. In other words, the plate edges diverge from the endadjacent the supply beam. Resistance wire 54 is arranged beneath theplate to heat it.

When the fabric is drawn from the supply beam across the plate, thelongitudinal pull on the fabric by the takeup roll will pull the fabrictight over the convex plate surface causing it to spread. The heatedsurface will set the fabric in the stretched condition.

If desired, the take-up beam may be equipped with rows of pins 55adjacent its ends to engage and hold the fabric side edges. If this isdone, the same equipment may be used for continuous or batch setting. Ifcontinuous setting is desired, the heating system for the plate isoperated. If a batch system is to be used, the plate will be left cold,but the fabric will be held transversely extended by the pins 55 untilthe beam is filled and the fabric is set.

A different stretching apparatus has been shown in FIGURES and 11. Here,the fabric 56 is delivered from a supply beam 57 driven by roller 58 andwound upon a take-up beam 59 driven by roller 60. The takeup driveroller, of course, will rotate at a faster rate than drive roller 58 soas to elongate the fabric. Intermediate the supply and take-up beamsthere is a plurality of rollers 61. Each roller 61 is of differentlength, the

rollers being arranged in a progressively lengthening sequence, with theshortest roller adjacent the supply beam and the longest adjacent thetake-up beam. Each roller has a peripheral row of pins 62 at each end.

The fabric is stretched transversely intermediate the supply beam andthe adjacent roller 61, and between each two adjacent rollers 61 toprovide a plurality of stages of transverse stretch. The transversestretch is accomplished by means of spiked conical rollers 63 which arelocated above the fabric path so that their spikes 64 engage theselvages of the fabric at the width it leaves the supply beam, orpreceding roller 61, as the case may be. The conical rollers 63 arearranged so they rotate generally at right angles to the path of travelof the fabric with cones at opposite selvages of the fabric rotating inopposite directions. The cones may be driven by belts 65 from aconvenient drive shaft (not shown).

With the apparatus shown in FIGURES l0 and 11 the fabric leaving thesupply beam 57 is caught by the first set of cone rollers, and, as thelower surfaces of the cones are moving outwardly relative to the fabric,the fabric will be stretched widthwise. The speed of the cones will beset to stretch the fabric sufficiently to bring the selvages out to thevertical plane of the: rows of pins on the next adjacent roller 61. Thissame operation will take place at each cone and roller combination toextend the fabric widthwise in a series of successive steps. When thefabric is extended to its full width at the last roller 61, it passesonto the take-up beam 59 where the edges are caught on pins 55 carriedat the ends of the beam. Thus, the fabric will be held extended on thebeam and the filled beam can be subjected to heat to stabilize thefabric.

A still further type of apparatus suitable for extending fabric bothlongitudinally and transversely is illustrated in FIGURES 12 and 13. Inthis form, the apparatus includes a supply beam 67 driven by driveroller 68 and a take-up beam 69 driven by drive roller 70. Fabric 71 iselongated in passing from the supply beam to the takeup beam by thespeed differential between the two beams. The transverse stretch isaccomplished by means of chains 72 and 73 which follow diverging pathsfrom the outer edges of the supply beam to the outer edges of the longertake-up beam. The chains carry pins 74 and 75 to engage the fabricselvages and progressively extend the fabric as the fabric moves fromthe supply beam to the take-up beam. The chains are trained oversprockets 76 and '77 on shafts 78 and 79 and move in vertical orbits.With this form of apparatus also, the take-up beam has rows of pins 80on its ends to hold the fabric under tension until it can be heat set.

While in the above several embodiments of the invention have beendisclosed, it will be understood that the details of construction shownand described are merely by way of example and the invention may takeother forms within the scope of the appended claims.

What is claimed is:

1. A stabilized spandex yarn with properties of reduced denier,increased yardage and reduced stretch over the spandex yarn from whichit was formed, said properties having been obtained by stretching theyarn in the range of 250% to 500% and stabilizing in stretched conditionby heat in the range of F. to 700 F.

2. A spandex yarn as claimed in claim 1, wherein the spandex yarn is acore yarn and is wrapped with a multifilament nylon cover yarn with 10to 50 turns of cover yarn per inch of core yarn.

3. A stabilized fabric composed at least in part of spandex yarns, thefabric having properties of reduced yarn denier, increased yardage andreduced stretch over the fabric from which it was formed, saidproperties having been obtained by stretching a fabric longitudinallyand transversely in the range of 30% to 250% and stabilizing the fabricin stretched condition by heat from 180 F. to 700 F.

4. A fabric as claimed in claim 3, wherein the spandex yarns are coreyarns and are wrapped with multifilament nylon cover yarns with 10 to 50turns of cover yarn per inch of core yarn.

References Cited UNITED STATES PATENTS Bechter 26-63 X Milne.

Smith 57-163 X Miles et a1. 57-152 X Schneller 57-152 Clarkson 57-163 XAnderson 26-68 Foster 57-152 Litzler 26-68 X Rnpprecht 57-163 XHumphreys 57-163 Burleson et al 57-152 X Marshall 57-163 Lathem et a157-163 Hermes 57-163 Chapman et a1. 66-202 XR Ibrahim 66-202 XR FRANK J.COHEN, Primary Examiner.

DONALD WATKINS, Assistant Examiner.

